Description:
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a single phase induction motor speed regulation with controlling motor torque by varying voltage across main winding with help of a series inductor. The present invention relates to a speed regulator circuit having inductors in series with the main winding to vary the voltage for controlling the speed or motor torque.
BACKGROUND AND PRIOR ART:
[002] The single phase induction motor has AC input. The single phase induction motor has rotor and stator. The single phase induction motor has only one phase on the stator winding. Hence the resulting magnetic field in a single phase induction motor does not rotate. For starting any type of motor there must be resulting magnetic field to create torque to rotate the rotor. In single phase induction motor without capacitor the field created by stator winding is positive in half cycle and negative in other half so resulting net field is zero so torque is also zero. Now when capacitor is added to the additional auxiliary winding of stator it creates field which leads by 90 degree to main winding field so the two fields which are 90 degrees to each other, resulting rotating field responsible for start of the fan motor. The capacitor used to start the motor after start may be taken out of circuit because as rotor is rotating each half field of stator creating field in rotor in same direction so producing net field not equal to zero and motor can run continuously if the switch off the power supply to the motor. In existing table, Wall, and pedestal fan single phase induction motor, speed of motor is controlled by tapping/looping points from different location of stator winding.
[003] Fig. 1 illustrates block diagram of existing system for speed/torque control in table, wall and pedestal fan single phase induction motor. The single phase induction motor has rotor and stator. The stator 100 has run winding (main winding) 101 and auxiliary winding 102 with a capacitor 103. During selection of low, medium, and high speed, the AC input is tab in between the coils to vary current and voltage in the main winding 101. The main winding 101 has four coils M1, M2, M3, M4 or poles. Similarly, the auxiliary winding 102 has four coils A1, A2, A3, A4 or poles.
[004] During Low speed selection, a supply live point or AC input 105 is connected via switch 104 with tapping between coil A2 and A3 in Auxiliary winding 102. The coil A1 and A2 are shifted to Main winding 101 which now becomes 6 pole (coil), M1, M2, M3, M4, A1, A2, i.e., and Auxiliary winding 102 is left only with two (2) poles A3, A4 (coil). There is coil imbalance in between the main winding 101 and the auxiliary winding 102 creates electrical imbalance between main winding 101 and the auxiliary winding 102 and generates noise in single phase induction motor.
[005] During medium speed selection: when supply of live AC point 105 is connected via the switch 104 with tapping between coil A1 and A2 in the auxiliary winding 102. Now coil A1 shifted to Main winding 101, i.e., Main winding 101 now becomes 5 poles (coil), i.e., M1, M2, M3, M4, A1 and the Auxiliary winding 102 is left only 3 poles (coils), i.e., A2, A3, A4. There is coils imbalance in between the main winding 101 and the auxiliary winding 102 which creates electrical imbalance and generates noise in single phase induction motor.
[006] During High speed selection: when supply of live AC point 105 connected via the switch 104 with common terminal of two windings. No Pole (Coil) shifting happens, i.e., Main winding 101 remain with 4 pole (coil), i.e., M1, M2, M3, M4 and the auxiliary (Start) winding 102 remains with 4 pole (coil), i.e., A1, A2, A3, A4. There is no coil imbalance in between the main winding 101 and the auxiliary winding 102. Therefore, there is no electrical imbalance between main 101 and auxiliary winding 102 and noise is also not generated.
[007] In the existing system or induction motor, unwanted noise is generated in Low and Medium speed point due to electrical imbalance in between the main winding and the auxiliary winding. Therefore, there is a requirement in the motor to have equal coil balance during low and medium speed selection point. Therefore, there is a need in the art to provide single phase induction motor with a mechanism to distribute equal coils in each speed point and varying flow of current in the windings depend upon the selection of speed point. Further, there is a need in the art to provide a single phase induction motor that is more simple and inexpensive, and which does not create noise and electrical imbalance.
OBJECTS OF THE INVENTION:
[008] The principal objective of the present invention is to provide a single phase induction motor having no electrical imbalance in both Main and Auxiliary winding.
[009] Another objective of the present subject matter is to provide speed regulator circuit in the single phase induction motor to control the motor torque.
[0010] Another objective of the present subject matter is to reduce/eliminate noise in induction motor at low and medium speed selection point due to electrical imbalance.
[0011] Another object of the present subject matter is to reduce temperature rise in the motor during load at low speed point.
SUMMARY OF THE INVENTION:
[0012] The subject matter disclosed herein relates to a single phase induction motor with rotor torque/speed control with the help of variable inductance voltage across the main winding with the help of a series inductor. The single phase induction motor has a stator and rotor. The stator is powered by an AC power source. The rotor rotates inside the stator upon generation of magnetic field. The stator has run winding (main winding) and an auxiliary winding (start winding). Further, a capacitor is provided to connect with the auxiliary winding in series upon selection of speed by a switch. The supply live point given is made to connect via switch for various speed points.
[0013] For regulating the speed at medium and low conditions, a speed regulator circuit is provided. At the medium speed point, the power supply point is connected via switch with a medium speed impedance circuit which is connected in series with the main winding. At low speed point, the power supply point is connected via switch with a low speed impedance circuit connected in series with the medium speed impedance circuit and the main winding.
[0014] In an aspect, the medium speed impedance circuit comprises a plurality of series connected inductive coils (SI 1.1, SI 1.2, SI 1.3, SI 1.4).
[0015] In an aspect, the low speed impedance circuit comprises a plurality of series connected inductive coils (SI 2.1, SI 2.2, SI 2.3, SI 2.4).
[0016] In an aspect, during low speed selection the impedance provided by speed regulator circuit is an aggregate of impedance (Z) provided by low speed impedance circuit, the medium speed impedance circuit and the main winding.
[0017] In an aspect, during medium speed selection the impedance provided by the speed regulator circuit is equivalent to impedance of the medium speed impedance circuit and the main winding.
[0018] In an aspect, the main winding and the auxiliary winding has equal number of poles.
[0019] In another embodiment the present subject matter relates to a method for controlling speed of a single phase induction motor. The method comprising connecting, by a switch, power source to a medium speed impedance circuit during medium speed selection; connecting, by the switch, the power source to a low speed impedance circuit during low speed selection; and connecting, by the switch, the power source directly to a main winding during high speed selection.
[0020] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0022] Fig. 1 illustrates block diagram of existing speed regulator circuit for speed /torque control in the Table, Wall and Pedestal fan induction motor; and
[0023] Fig. 2 illustrates block diagram of the speed regulator circuit with series impedance for speed/torque control in the Table, Wall and Pedestal fan single phase induction motor.
[0024] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0025] The subject matter disclosed herein relates to a single phase induction motor with rotor torque/speed control with the help of varying voltage across main winding with series inductor. The single phase induction motor has a stator and rotor. The stator is powered by an AC power source. The rotor rotates inside the stator upon generation of magnetic field. The stator has run winding (main winding) and an auxiliary winding (start winding). Further, a series of inductor is connected with the main winding having different impedance value in series upon selection of speed by a switch.
[0026] The subject matter disclosed herein relates to a speed control circuit for a single phase induction motor with rotor torque/speed control by varying series inductor with main winding. With the present circuit, the electrical imbalance in main winding and auxiliary winding of the single phase induction motor is eliminated and reduction /elimination of noise of motor at low and medium speed is achieved.
[0027] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0028] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0029] Fig. 2 illustrates circuit diagram for speed/torque control in the single phase induction motor which can be provided in Table, Wall and Pedestal fan. The single phase induction motor has a stator and rotor. The stator is powered by an AC power source. The rotor rotates inside the stator upon generation of magnetic field. The speed control circuit 200 of the single phase induction motor is illustrated in the fig. 2. The stator has run winding (main winding) 201 and an auxiliary winding (start winding) 202. Exemplary, the main winding 201 has four coils or poles M1, M2, M3, M4. Similarly, the auxiliary winding 202 has four coils A1, A2, A3, A4 or poles. Further, number of coils in the main winding 201 and the auxiliary winding 202 may vary from four coils, however, the number of coils or poles remain same in both the main winding 201 and the auxiliary winding 202. On the basis of the impedance, each coil has different number of turns to increase or decreases the value of impedance. The single capacitor 203 is connected in series with auxiliary winding 202 to introduce a phase shift between the magnetic field of the main (running) winding 201 and the auxiliary winding 202. Further, the single capacitor 203 connects with the auxiliary winding 202 in series upon selection of speed by a switch 204. The switch 204 is provided for controlling current flow in the stator windings.
[0030] Exemplary number of turns in the coil and impedance value with current value is provided in below table 1. However, the actual value may differ from the given exemplary values. The table 1 shall be read in conjunction with fig. 2. The values for main winding 201, auxiliary winding 202 and inductive coils:
TABLE 1
Exemplary values for one fan
Main Winding:
M1, M2, M3, M4 Big coil: 280 to 350 turns
Small coil: 130 to 170 turns 100 to 140 ohm 0.30 to 0.40 Amp
SI 1.1, SI 1.2, SI 1.3, SI 1.4 Big Coil: 150 to 210 turns
Small coil: 50 to 130 turns 140 to 170 Ohm 0.24 to 0.25 Amp
SI 2.1, SI 2.2, SI 2.3, SI 2.4 Big coil: 40 to 80 turns
Small coil: 20 to 40 turns 45 to 65 Ohm 0.25 to 0.35 Amp

Auxiliary Winding:
A1, A2, A3, A4 Big coil: 180 to 260 turns
Small coil: 130 to 170 turns 80 to 100 Ohm 0.30 to 0.40 Amp

Exemplary values for another fan
Main Winding:
M1, M2, M3, M4 Big coil: 400 to 500 turns
Small coil: 150 to 230 turns 150 to 200 ohm 0.27 to 0.31 Amp
SI 1.1, SI 1.2, SI 1.3, SI 1.4 Big Coil: 30 to 70 turns
Small coil: 40 to 90 turns 40 to 60 Ohm 0.26 to 0.30 Amp
SI 2.1, SI 2.2, SI 2.3, SI 2.4 Big coil: 10 to 40 turns
Small coil: 20 to 80 turns 15 to 30 Ohm 0.27 to 0.31 Amp

Auxiliary Winding:
A1, A2, A3, A4 Big coil: 300 to 450 turns
Small coil: 150 to 230 turns 110 to 150 Ohm 0.21 to 0.33 Amp

[0031] Referring to fig. 2 and above mentioned table 1 together, the characteristics related to the Main winding 201 and Auxiliary winding 202 are given. In the table for Main Winding 201, the four poles are denoted by M1, M2, M3, and M4. Innovatively, the present main winding 201 has a series of inductive coils/poles that are denoted by SI 1.1, SI 1.2, SI 1.3 and SI 1.4 (combindely referred as medium speed impedance circuit 206), and SI 2.1, SI 2.2, SI 2.3 and SI 2.4 (combindely referred as low speed impedance circuit 207). The medium speed impedance circuit 206 comprises a plurality series connected inductive coils/poles SI 1.1, SI 1.2, SI 1.3 and SI 1.4. Similarly, the low speed impedance circuit 207 comprises a plurality series connected inductive coils/poles SI 2.1, SI 2.2, SI 2.3 and SI 2.4. Where the medium speed impedance circuit 206 are connected in series with the main winding 201 when medium speed point is selected. Where the low speed impedance circuit 207 are connected in series with the main winding 201 and the medium speed impedance circuit 206 when low speed point is selected.
[0032] The Auxiliary winding 202 has four poles which are denoted by A1, A2, A3 and A4.
[0033] Working and functioning of the present speed control circuit 200:
[0034] During High speed point selection, supply live AC point 205 connected with the switch 204 with 4 poles M1, M2, M3, M4 of the Main Winding 201 and 4 poles A1, A2, A3, A4 of the auxiliary winding 202. The capacitor 203 is connected in series with the auxiliary winding 202 in order to provide a phase shift between the magnetic field of main winding 201 and the auxiliary winding 202. When the high speed is opted, the switch 204 connects the power source 205 directly to the main winding 201 of the stator. As the number of poles in the main winding 201 and auxiliary winding 202 are same, no electrical imbalance happens and as a result no noise is generated.
[0035] To eliminate the electrical imbalance in the main winding 201 and auxiliary winding 202 during medium speed point and low speed point, the present speed regulator circuit 200 comprises a medium speed impedance circuit 206 and a low speed impedance circuit 207. The medium speed impedance circuit 206 or low speed impedance circuit 207 are used for lowering the voltage in the main winding 201 by increasing the total impedance. To increase the total impedance of the speed regulator circuit 200, the medium speed impedance circuit 206 are connected in series with the main winding 201. Similarly, the low speed impedance circuit 207 are connected in series with the medium speed impedance circuit 206 and the main winding 201 to further increase the total impedance.
Total impedance (Ztotal) is highest in the low speed point. In the present speed regulator circuit 200, the total impedance follows the below relation.
Zlow>Zmedium>Zhigh
[0036] During Medium speed point, supply live point 205 connected via the switch 204 with the medium speed impedance circuit 206 connected in series with the main winding 201. The medium speed impedance circuit 206 is connected in series with the main winding 201. The added medium speed impedance circuit 206 having impedance value which causes voltage drop in the voltage supply and dropped remaining voltage is given to the main winding 201. In this case, the voltage across the main winding 201 gets reduced as per the inductive reactance or impedance of series inductor (medium speed impedance circuit 206) and simultaneously the speed of the motor reduces as the speed/torque becomes directly proportional to the voltage across main winding 201. Further, the number of poles in the main winding 201 remain the same as of the auxiliary winding 202 which is 4. As there is no pole difference among main winding 201 and the auxiliary winding 202, no electrical imbalance happens and as a result noise problem is eliminated.
[0037] During Low speed point, the supply live point 205 is connected via switch 204 with the low speed impedance circuit 207 connected in series with the medium speed impedance circuit 206 and the main winding 201. The added low speed impedance circuit 207 in the series connection of the medium speed impedance circuit 206 and the main winding 201 having impedance value which further causes voltage drop in the voltage supply and dropped remaining voltage is given to the main winding 201. At the low speed selection, the impedance provided by the speed regulator circuit 200 is an aggregate of impedance provided by medium and low speed point. The inductive coils 207 at the low speed impedance circuit are connected in series with each other. At the time of low speed selection, the switch 204 present, connects the power source (AC) 205 to the second terminal of the low speed impedance circuit. In this case, the voltage across main winding 201 further reduces and simultaneously the speed of the motor reduces. With no pole difference, no electrical imbalance happens and as a result noise problem is eliminated.
[0038] In another embodiment of the present subject matter, the present method for controlling speed of the single phase induction motor is provided.
[0039] The present method includes steps for controlling speed of a single phase induction motor. The method comprises connecting, by a switch (204), power source (205) to a medium speed impedance circuit (206) during medium speed selection; connecting, by the switch (204), the power source (205) to a low speed impedance circuit (207) during low speed selection; and connecting, by the switch (204), the power source (205) directly to a main winding (201) during high speed selection.
[0040] The present subject matter provides an electric motor with speed/torque of motor regulation by varying voltage across main winding 201 with series inductor by controlling series impedance of induction motor. Further, present subject matter provides an induction motor without imbalanced electrical load/Eliminated imbalanced electrical load.
[0041] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

Claims:We claim:
1. A speed regulator circuit (200) for a single phase induction motor, the speed regulator circuit (200) comprising:
a main winding (201) and an auxiliary winding (202) powered by a power source (205);
a capacitor (203), electrically connected in series with the auxiliary winding (202), to introduce a phase shift between the magnetic field of the main winding (201) and the auxiliary winding (202);
a switch (204) provided for controlling current flow by varying impedance of the main winding (201);
a medium speed impedance circuit (206) connected in series with the main winding (201); and
a low speed impedance circuit (207) connected in series with the medium speed impedance circuit (206) and the main winding (201).

2. The speed regulator circuit (200) as claimed in claim 1, wherein the medium speed impedance circuit (207) comprises a plurality of series connected inductive coils (S1.1, S1.2, S1.3, S1.4).
3. The speed regulator circuit (200) as claimed in claim 1, wherein the low speed impedance circuit (207) comprises a plurality of series connected inductive coils (S2.1, S2.2, S2.3, S2.4).

4. The speed regulator circuit (200) as claimed in claim 1, wherein during low speed selection the impedance provided by speed regulator circuit (200) is an aggregate of impedance (Z) provided by low speed impedance circuit (207), the medium speed impedance circuit (206), and the main winding (201).
5. The speed regulator circuit (200) as claimed in claim 1, wherein during medium speed selection the impedance provided by the speed regulator circuit (200) is equivalent to impedance of the medium speed impedance circuit (206) and the main winding (201).
6. The speed regulator circuit (200) as claimed in claim 1, wherein the main winding (201) and the auxiliary winding (202) has equal number of poles.
7. A method for controlling speed of a single phase induction motor, the method comprising:
connecting, by a switch (204), power source (205) to a medium speed impedance circuit (206) during medium speed selection; and
connecting, by the switch (204), the power source (205) to a low speed impedance circuit (207) during low speed selection; and
connecting, by the switch (204), the power source (205) directly to a main winding (201) during high speed selection.

8. The method as claimed in claim 7, wherein the medium speed impedance circuit (206) comprises a plurality of series connected inductive coils (S1.1, S1.2, S1.3, S1.4), the medium speed impedance circuit (206) connected in series with the main winding (201).
9. The method as claimed in claim 7, wherein the low speed impedance circuit (207) comprises a plurality of series connected inductive coils (S2.1, S2.2, S2.3, S2.4), the low speed impedance circuit (207) connected in series with the medium speed impedance circuit (206) and the main winding (201).